I. Field of the Invention
The present invention generally relates to telecommunication systems, and more particularly to Session Initiation Protocol (“SIP”) extensions for call control and resource status monitoring in voice trading systems that include turrets and turret switching systems.
II. Description of the Related Art
A turret system is a specialized key telephony switching system that allows a relatively small number of users to access a large number of external lines and provides enhanced communication features such as hoot-n-holler, push-to-talk, intercom, video, and large-scale conferencing. These features are often utilized in the financial industry such as trading floor environments, as well as security/law enforcement, public safety utilities, healthcare, and customer support (e.g., contact centers) environments.
Users interface with a turret system through a turret device, which is a phone-like desktop device with multiple handsets and speakers and multiple buttons. A turret is either implemented in dedicated hardware (sometimes referred to as a “hard” turret) or a general-purpose computer (sometimes referred to as a “soft” turret). With the advent of Voice over Internet Protocol (“VoIP”), VoIP turret devices have moved from a fixed environment of dedicated voice communications trading resources to a more virtualized trading environment across multiple sites. This virtual environment allows resources to be shared dynamically, when and where required, across a global corporate enterprise.
SIP is an application-layer control (i.e., signaling) protocol for creating, modifying, and terminating interactive communications sessions, such as Internet telephony calls, with one or more participants and is defined in RFC-3261, “SIP: Session Initiation Protocol.” SIP-based communication architectures provide the ability to signal and communicate between telephony systems in collaboration with other protocols such as Session Description Protocol (“SDP”) and Real-Time Protocol (“RTP”). SDP describes streaming media initialization parameters in an ASCII string and multimedia communication sessions for the purposes of session announcement, session invitation, and parameter negotiation. SDP is defined in RFC-4566, “SDP: Session Description Protocol.” RTP is a standardized packet format for delivering audio and/or video data over IP networks and is defined by RFC-3550. RFC-3261, RFC-4566, and RFC-3350 are hereby incorporated by reference in their entirety.
Supporting additional functionality, such as call control and resource status monitoring, for turrets and turret switching systems using SIP requires extensions to the base SIP protocol.